Machine for centrifugally casting tubular metal bodies

ABSTRACT

Machine for centrifugally casting tubular metal bodies in a rotary mould rotating about an axis inclined at 1 to 10 percent. The machine includes a tubular pouring conduit having an inlet and an outlet for the molten metal and upwardly inclined from the inlet to the outlet at the same angle as the mould axis. Relative movement between the pouring conduit and mould causes the outlet to pour metal into the mould from one end to the other of the latter.

nit ttes v atent Guenmi 1 Mar. 14 1972 [54] ACHHNE FlUR CENTRIFUGAILLY1,351,767 9/1920 Ladd ..164/117 CAS'HNG TUBULAR METAL BOUHES 7,4969/1923 Per y 164/117 X 3,162,909 12/1964 Sylvester... 164/337 X [72]Inventor: lEraldo Serahno Guenzi, Pont-A-Mousson, 3,297,436 9 7 Duwez164/1 14 x France 3,299,480 1/1967 Woodburn et al.. ....249/l09 X 7Assignee: Cenre de Recherches dc Pon1 A MouSson, 1,858,478 5/1932Carnngton .164 17 Pont-A-Mousson, France I Primary ExammerR. SpencerAnnear [22] Filed: Oct. 21, 1969 Attorney-J. Delattre-Seguy [21] Appl.No.: 868,671 [57] ABSTRACT Machine for centrifugally casting tubularmetal bodies in a rokg 2 5 tary mould rotating about an axis inclined atl to 10 percent. [58] i 298 299 The machine includes a tubular pouringconduit having an 164/301 6 inlet and an outlet for the molten metal andupwardly inclined from the inlet to the outlet at the same angle as themould axis. Relative movement between the pouring conduit and mould [56]References Cited causes the outlet to pour metal into the mould from oneend to UNITED STATES PATENTS the other of the latter.

535,598 3/1895 Potter ..164/337 3 Claims, 7 Drawing Figures t o m Q91 ll 0 l .l c is MACEHINE EOE CENTEIIEUGAEEY CASTING TlUlBlUlLAlli METALBODIES The present invention relates to machines for centrifugallycasting metal tubular bodies in a tubular mould rotating about its axis.More particularly, the invention relates to the type of machines whichcomprise a channel supplying the mould with liquid metal and a devicewhich produces a relative movement of translation between the channeland the mould so as to pour the liquid metal in an even manner from oneend of the mould to the other.

The known machines of this type which are for'example, but notexclusively, applicable to the production of cast iron pipes have aliquid metal supply channel of the open type, that is, having a crosssection roughly in the shape of a horseshoe. The liquid metal tlows bygravity, along this channel which is of great length and slightlyinclined, its pouring end being slightly lower than its upstream end.The mould is roughly parallel to the supply channel. Theses machinesinclude many improvements for improving the quality of the cast parts,for better controlling the amount of metal poured, for facilitating themaintenance or servicing of the pouring channel and for increasing theproduction rates.

In the research carried out by the applicant for achieving the foregoingimprovements, a new method for centrifugally casting was discoveredwhich satisfies these requirements and considerably simplifies theconstruction of the machine.

The object of the invention is to provide a method for centrifugaliycasting metal tubular bodies of the type in which the liquid metal ispoured from one end to the other of the rotatable mould whose axis isroughly horizontal, wherein the liquid metal is injected under pressurein the form of a stream having a constant section and an adjustableflow.

Preferably, according to another important characteristic, the liquidmetal is injected under pressure in a slightly ascending stream at aslope of between I and 10 percent and the pouring is stopped by stoppingthe pressure so as to stop the movement of this ascending stream ofliquid metal, the metal being maintained liquid by heat insulation untilthe mould is once again available for receiving the pour of liquidmetal, and the injection under pressure is resumed.

Another object of the invention is to provide a machine forcentrifugally casting metal tubular bodies by means of theaforementioned method, said machine being of the type having a liquidmetal container, a rotatable mould and a channel for pouring the liquidmetal intended to penetrate the mould, the channel having an axis whichis roughly parallel to that of the mould and a length exceeding that ofthe mould and being moved in translation relative to the mould forpouring the liquid metal in an even manner from one end of the mould tothe other. In the machine according to the invention, the liquid metalcontainer or pouring vessel is higher than a rigid rectilinear tubularconduit to which said vessel is connected, said conduit having a pouringorifice at its downstream end.

According to another feature of the invention, said conduit is slightlyupwardly inclined in the direction from the end thereof connected tosaid vessel to the pouring end.

Owing to the invention, the conditions under which the liquid metal issupplied are more precise. Moreover, the construction and maintenance ofthe machine are considerably simplified.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. II is a diagrammatic assembly view of a machine according to theinvention;

FIG. 2 is a detail view ofa tubular conduit partly cut away;

FIG. 3 is a detail sectional view showing the pouring of the metalinside the mould;

FIG. 4 is a diagrammatic view of a modification of the liquid metalsupply device having a vessel pouring metal under pressure;

FIG. 5 is a diagrammatic assembly view, similar to FIG. 1, of ahorizontal machine;

FIG. 6 is a detail cross-sectional view, to an enlarged scale, of thepouring spout or end of a tubular conduit for a horizontal machine, and

FIG. 7 is a diagrammatic view of a modification of the liquid metalsupply vessel.

According to the embodiment shown in FIGS. l and 2, the invention isshown to be applied to a machine for centrifugally casting cast ironpipes in a tubular mould or shell A having an axis XX. The mould ismounted inside a carriage B which is movable in translation by a jack orpiston and cylinder arrangement C. The mould A is driven in rotation bya motor D.

The metal mould A receives liquid metal which is for example supplied bya tiltable vessel E of known type.

According to the invention, the device supplying liquid metal to themachine is arranged as follows: a container t for the liquid metal, forexample open in its upper part, is secured below the tiltable vessel E.In its lower part, the vessel E has a pouring nozzle 2 connected to thetubular conduit 3 of great length exceeding that of the mould or shellA. The container 1 into which the vessel E pours the metal is thushigher than the tubular conduit and therefore produces a pressure head.

This conduit, which is adapted to conduct liquid metal inside the mouldA, is slightly upwardly inclined toward the carriage B, its downstreampouring end being higher than its upstream end connected to thecontainer 1. The slope or inclination of the conduit 3 is between 1 andpercent and preferably of the order of 3-4; percent.

Also according to the invention, the axis XX of the mould A is inclinedthe same degree and is parallel to the tubular conduit 3.

More particularly, the conduit 3 is composite and comprises (FIG. 2) inthe following order from the interior to the exteria refractory tube 4of great length which can be either in one piece or comprise elementswhich are assembled in end-to-end relation by sleeves or fitted insideeach other;

- a heat-insulating refractory case 5 which is preferably flexible andfor example comprises a felt of mineral wool sur rounding the tube 4 andheld around the latter for example by means of spaced rings 6 ofadhesive tape or adhered to the tube;

- an outer metal sheath 7, for example in two parts which are assembledin a diametral joint plane 8, this sheath terminates in a flange 9 forconnection to the nozzle 2 of the container 1.

Note that the tube 4 is freely mounted inside the coaxial sheath 7relative to which it is movable. This is permitted by the flexiblerefractory case 5. The tube 4, which open at both ends extends beyondthe case 5 and the sheath 7 a certain length at its downstream end,namely the higher end (this extension is provided to preclude the streamof liquid metal from touching and harming the case 5 and the sheath 7).

The tubular conduit 3 is carried by with drawable supports MB of thetype described in French Pat. No. 1,002.38). These supports arepivotable so as to allow the passage of the carriage B.

The centrifugal casting machine is completed by a mould stripping andextracting device for the cast tube F constituted by an extractingcarriage (not shown) of known type which moves on the other side of thecontainer 1 to the carriage B of the machine.

The machine operates in the following manner (FIG. I and 3):

With the mould A rotated at high speed, the container 1 is filled withliquid metal G up to an upper level N. As the container is higher thanthe conduit 3, the downstream end of this conduit 3 being at a.substantially lower level than the upper end of the container 1, theconduit 3 is completely filled with liquid metal which flows at a givenpressure in the mould A. The carriage B moves toward the container 1, inthe known manner, so that the mould A is supplied with metal from oneend to the other. During the whole of the pour the conduit 3 remainsfull of metal G. This metal issues from the conduit 3 at an initialspeed of V (HO. 3) which enables it to rise up to the slope of the mouldA. Owing to the inclination x of the mould; the metal G is braked (FIG.3) along a longitudinal distance a which enables it to be driven inrotation.

When the pouring end of the tubular conduit 3 reaches the other end ofthe mould A, that is, the lower end of the latter, the pouring isstopped by the fact that a level (N) of the metal G is reached in thecontainer 1 which is equal to that of the upper end of the tubularconduit 3. The difference between the levels (N -N) correspond to theheight required to afford the desired flow of metal.

During the solidification of the metal inside the mould A, its coolingand the extraction of the produced pipe F, the tubular conduit 3 remainscompletely filled with liquid metal which is at a sufficiently hightemperature, at least during 2 or 3 minutes owing to the action of therefractory case 5,

As soon as the mould A is ready for a further casting after the tube Fhas been stripped from the mould it is merely necessary to once againfill the container 1 up to a certain upper level to restart the castingas mentioned hereinbefore.

Thus the procedure is to cast intermittently while maintaining thetubular conduit constantly full of liquid metal, even during thestoppages between pouring the duration of which are reduced to theminimum.

Note that the pouring is always carried out under pressure, but under apressure which decreases as the level of the liquid metal in thecontainer 1 drops, consequently, the metal flows as a rising liquidstream whose section is constant and corresponds to that of the tube 4but whose flow decreases as the pressure drops. This pressure and flowremain known at each moment since the upper level of the liquid metal inthe container l is known at the start of the pouring and the lower levelupon stopping the pouring is known which corresponds to that of thedownstream end of the tube 4.

Note, moreover, that the inner tube 4 and the outer sheath 7 of thetubular conduit 3 have substantially different expansions owing to thefact that their temperatures are very different (the inner tube 4 beingat a temperature higher than l,O00 C. and the sheath 7 being at atemperature of the order of 400) and that the coefficients of expansionare very different, that of the steel sheath being much higher than thatof the refractory tube 4. Owing to the freely movable mounting of thetube 4 inside the sheath 7 and to the flexibility of the heat-insulatingcase 5, the tube 4 and the sheath 7 are free to expand in a differentialmanner relative to each other irrespective of the temperature range.Note, furthermore that as the highest temperature corresponds to thelowest coefficient of expansion there is a certain compensation in theresulting expansion; that of the inner tube 4 cannot be different fromthat of the sheath 7.

The main advantages afforded by the invention are the following:

Owing to the tubular conduit 3, to the container 1 higher than theconduit 3 and to the rising slope of the tubular conduit 3, the streamof liquid metal has a constant section which corresponds to that of thetube 4. Since, moreover, the pressure of the pouring is constantly knownby the level. i

As furthermore the pressure of the pouring is constantl known by thelevel of the metal in the container 1, the amount or flow of the liquidmetal poured into the mould A is controlled with precision. Further,owing to these same characteristics and owing to the rising slope of thecarriage B of the mould A, the flow of the metal into the mould isregular and calm because it is braked by rising slope of the mould.Consequently, a perfectly sound cast tube F is obtained. Further, thecast tubes all have the same weight within small tolerance since it ispossible to control with precision the amount of metal poured into eachmould by the supervision of the upper level of the start of the pouringand of the lower level at the end of the pouring in the container 1.

The flow out of contact with air in the conduit 3 avoids oxydation ofthe metal. The absence of a coating inside the tube 4 avoids thecarrying along of coating products in the liquid metal and indesirableinclusions in the cast tube F.

Owing to the connection of the conduit 3 to the lower part of thecontainer 1, the poured metal has no dirt and slag which are supernatantin the upper part of the container 1.

Owing to the constant filling of the tubular conduit 3 with metalremaining liquid, even during the stoppages of the pouring, many deadwaste periods are eliminated relative to casting in known openhorse-shoe sectioned channels since the tubular conduit requires nomaintenance and no repairs between two successive pourings. The pouringinterruptions are thus reduced to a minimum. This is advantageous notonly as concerns the production rate, which is considerably increased,but also as concerns the temperature of the metal in the container lwhich is constantly renewed. In other words, the metal hardly has timeto cool down in the container 1 during the pouring interruptions so thatthe metal is always poured at the highest possible temperature, which isbeneficial for the quality of the parts cast in the mould A. r

As the metal always remains liquid in the heat-insulated conduit 3, onlythe amount of metal corresponding to the weight of a tube F is pouredand losses of cooled and solidified metal in the supply channel areeliminated. Thus the saving in metal relative to the known method withan open horse-shoe sectioned channel can be considerable.

Lastly, the tubular conduit 3 is very simple in construction very cheapto make and requires no upkeep since it can be easily and cheaplyreplaced after a certain period of service.

The invention thus affords considerable advantages as to theconstruction and the operation of the centrifugal casting machine.

According to a modification shown in F IG. 4, the container 1 isreplaced by a pouring ladle or vessel 11 operating under pressure havinga spout 12 for receiving the liquid metal and a pouring spout 13. Thelatter is connected to the flange 9 of the tubular conduit 3. Thepouring vessel 11 is hermetically closed in its upper part by a cover 14through whichextends a conduit supplying fluid under pressure forexample air or a neutral gas. This vessel of a well known type,constituting a tea-pot, is secured to a stand and supplies the tubularconduit 3 in perfectly sound metal since the slag'and the vslurries aresupernatant in the upper part, as is the case with the container 1.

The pouring vessel 1] permits regulating the flow of the pouring thestart of the pouring and the end of the pouring with even greaterprecision than before since it is sufficient to vary in a controlledmanner the pressure of the fluid in the conduit 15 to cause the metal torise in the tubular conduit 3 or, on the other hand, to maintain itstationary in this conduit, the pressure being then very low. It is easyto achieve constant a flow of the pouring by increasing the pressure ofthe fluid in the conduit 15 as the pouring ladle l l empties.

According to the embodiment shown in FIG. 5, instead of having a risingslope, the tubular conduit 3 and the carriage B and the mould A areperfectly horizontal. This has the advantage of facilitating theconstruction. But in this case, instead of the tubular conduit 3 beingopen at its pouring end, it has a bottom 16 and a pouring orifice 17extending through the cylindrical wall of the tube near an uppergeneratrix in the neighborhood of this bottom 16 (see thecross-sectional view shown in FIG. 6). Preferably, the axis of theorifice 17 is inclined at an angle g relative to a horizontal diameter.This arrangement avoids that the tubular conduit become empty during astoppage of the pouring. With the conduit 3 connected to, for example, acontainer, such as l, but if desired also to a pouring vessel employingpressure, such as 11, the liquid metal under pressure is projectedupwardly inside the mould A in an oblique direction of angle 3 whichenables it to drop back tangentially into the wall of the mould A. Inthis way, there is achieved a braking of the poured metal and itsimmediate driving in rotation when it reaches the wall of the mould A.As in the preceding case, the stoppage of the pouring of a container,such as l, is achieved when the level of the metal in the container 1 isat the height of the orifice l7 and if a pouring vessel, such as B11, isemployed, when the pressure of the fluid in the conduit is suitablyreduced.

Note that in order to completely empty the tubular conduit 3 at the endof a station it is possible to proceed either by direct emptying in thelower part of the container 1 or by tiltmg.

For emptying or draining, an orifice closed by for example a refractoryplug is provided in the lower part of the container 1.

For tilting, instead of the container 1 or the pouring vessel 11 beingmounted on a fixed stand, they are mounted on rollers which permit theirtilting p. In this case the container and the pouring vessel preferablyhave the shape of a barrel having rolling rings carried by rollers whoseaxis are orthogonal to the tubular conduit 3 so as to allow theinclination of this conduit in a downwardly sloping manner so as tocompletely empty it by way of its downstream end. In the case of apouring vessel employing pressure, the pressure of the fluid is reducedinside the pouring vessel and the conduit 3 can be inclined with aupward slope which is still greater so as to be emptied in the vessel.

Instead of the rolling rings mounted on rollers it is also possible toprovide horizontal journals allowing the container 1 to tilt.

According to the modification shown in FIG. 7, the supply of liquidmetal is achieved by means of a vertical tube 118 having a relativelygreat height H and connected to the flange 9 of the conduit 3 andsurmounted by a shallow pouring vessel 19.

In this case, the variation in the level of the metal G in the vessel 19on the course of pouring has little influence on the pressure and theflow, above all if the height H is great. The pressure remainspractically constant and corresponds to the height H of liquid metal inthe tube I8. Consequently, the pouring is effected with a constant flow.

Although specific embodiments of the invention have been described, manymodifications and changes may be made therein without departing from thescope of the invention as defined in the appended claims;

What we claim is:

ll. A machine for centrifugally casting tubular metal bodies, comprisinga rotatable mound having an axis of rotation, a rigid tubularpouringconduit having an inlet adjacent one end of said conduit forreceiving molten metal and a pouring outlet adjacent an opposite end ofsaid conduit for pouring the molten metal inside the mould, said conduithaving an upward inclination from said inlet to said outlet and saidaxis having the same inclination as said conduit inclination, saidconduit and said mould being relatively movable between a position inwhich said outlet is within said mould and adjacent one end of saidmould and a position in which said outlet is adjacent an opposite end ofsaid mould, and means for causing said relative movement whereby moltenmetal can be poured from said one end to said opposite end of saidmould.

2. A machine as claimed in claim I, wherein said inclinations are 1-10percent.

3. A machine as claimed in claim 2, wherein said inclinations arebetween 3 and 6 percent.

1. A machine for centrifugally casting tubular metal bodies, comprisinga rotatable mould having an axis of rotation, a rigid tubular pouringconduit having an inlet adjacent one end of said conduit for receivingmolten metal and a pouring outlet adjacent an opposite end of saidconduit for pouring the molten metal inside the mould, said conduithaving an upward inclination from said inlet to said outlet and saidaxis having the same inclination as said conduit inclination, saidconduit and said mould being relatively movable between a position inwhich said outlet is within said mould and adjacent one end of saidmould and a position in which said outlet is adjacent an opposite end ofsaid mould, and means for causing said relative movement whereby moltenmetal can be poured from said one end to said opposite end of saidmould.
 2. A machine as claimed in claim 1, wherein said inclinations are1- 10 percent.
 3. A machine as claimed in claim 2, wherein saidinclinations are between 3 and 6 percent.